mkosi: use obscpio directory as source if present

When using the obs_scm service the content will be unpacked in
SOURCES/foobar/ but mkosi will run from SOURCES/ and not find the recipes.
If SOURCES/foobar.obsinfo is present and SOURCES/foobar/mkosi.conf is also
present, then use SOURCES/foobar/ as the source dir, so that we can
store recipes in git and use obs_scm.

build-recipe-mkosi

@@ -89,6 +89,16 @@ recipe_build_mkosi() {
         fi
     fi
 
+    # If we are running with the obs_scm service, the sources will be unpacked in a directory
+    # in SOURCES/, so try to find the right one, by checking where the top level mkosi.conf is.
+    workdir="$TOPDIR/SOURCES/"
+    for d in "$TOPDIR"/SOURCES/*.obsinfo; do
+        if [ ! -d "${d%.obsinfo}" ]; then continue; fi
+        if [ ! -f "${d%.obsinfo}/mkosi.conf" ]; then continue; fi
+        workdir="${d%.obsinfo}"
+        break
+    done
+
     local image_version=""
     if [ -n "$RELEASE" ]; then
         image_version="--image-version=${RELEASE}"
@@ -97,7 +107,7 @@ recipe_build_mkosi() {
         image_version="--image-version=0"
     fi
     set -- mkosi \
-        --directory "$TOPDIR/SOURCES" \
+        --directory "$workdir" \
         --default \
         "$RECIPEFILE" \
         $RELEASE_ARG \